postgres deadlocks

My postgres deadlocked again today.  Logs indicated that before the
nightly vacuum -z everything was fine, but after it was locked.  The
postgres.log contained the end of the vacuum which appeared to be
consistant with the other vacuums in the log.  A ps showed no vacuuming
processes, but it did show one 'idle in transaction'.  This problem last
happened in Februrary when I was using 7.0.3.

 select version();
                               version
---------------------------------------------------------------------
 PostgreSQL 7.1.2 on i686-pc-linux-gnu, compiled by GCC egcs-2.91.66
(1 row)


[root@p1 /var/log] ps ax | grep postgres
16973 ?        S      0:36 postgres: user2 owl 127.0.0.1 idle
17105 ?        S      0:01 postgres: user2 owl 127.0.0.1 idle
17122 ?        S      1:51 postgres: user2 owl 127.0.0.1 idle
17302 ?        S      1:19 postgres: user2 owl 127.0.0.1 UPDATE waiting
17453 ?        S      0:32 postgres: user2 owl 127.0.0.1 idle
18202 ?        S      0:03 postgres: user2 owl 127.0.0.1 idle
18351 ?        S      0:12 postgres: user2 owl 127.0.0.1 idle in
transaction
18352 ?        S      0:00 postgres: user2 owl 127.0.0.1 idle
 7137 ?        S      0:00 postgres: user2 owl 127.0.0.1 idle

--
Joseph Shraibman
jks@selectacast.net
Increase signal to noise ratio.  http://www.targabot.com